[Icecast] converting mp3's to aac+ or ogg

Chris MacDonald chris at thoughtsoft.net
Sun Jun 25 22:09:36 UTC 2006

Yeah, ezstream is a source client just like ices0, but the manner in 
which they go about processing files or playlists may differ. I don't 
know too much about ices0 but in the configuration for ezstream you can 
either specify a single file to stream or you can point it to an m3u 
playlist and it will play though that, I'm not sure this is compatible 
with how you currently queue media.

In terms of quality, I'm pretty picky which is why I wanted my source 
media in a lossless format. I chose flac but there are others, think wav 
+ compression; tracks I archive are usually 50-80% of their raw size, of 
course this varies from track to track. In your case going from mp3 to 
ogg, your ability to notice a difference will depend on the bitrate of 
the source mp3 and the resultant ogg stream. Something like a 256kbps 
vbr mp3 to a q3 (~110kbps vbr) ogg vorbis stream will still sound fine 
(I did this before deciding to do al my archiving in flac), but if you 
took a 128kbps mp3 and did the same you'd notice the change. Again, it 
varies from person to person and I'd imagine you'd just have to try it 
yourself to see what you'd like, it's less a science and more a preference.

The box that does my re-encoding on is an AMD 1800 with 512MB RAM and 
also does icecast, apache, mysql, sendmail, pretty much the whole 
shebang and I haven't had a problem. Though, mind you I'm only 
re-encoding for one stream whereas you'd be doing multiple streams. The 
flac decoder seems content with ~2% of the processor and the ogg encoder 
seems to like ~40% and again, this is hardly a science and undoubtedly 
'your mileage will vary'.


Dave wrote:
> Hi Chris,
>    Yes that helps a lot, thanks. I'm currently using ices0, which 
> worked fine when all i wanted to stream was mp3's. You've sold me on 
> ogg, and ezstream can it work as ices0 does? As i said i'd really not 
> like to do all this reencoding again, how much of a quality loss will 
> i be looking at if i go from mp3 to ogg? I'm not familiar with the 
> flac format at all. Does it have any kind of compression, i'd rather 
> not have something like all these wavs around or similar if i could 
> help it. As for the box how much of a hit will it take? What kind of 
> machine do you use for your encoding?
>    Thanks.
> Dave.
> ----- Original Message ----- From: "Chris MacDonald" 
> <chris at thoughtsoft.net>
> To: "Dave" <dmehler26 at woh.rr.com>
> Cc: <icecast at xiph.org>
> Sent: Sunday, June 25, 2006 4:46 PM
> Subject: Re: [Icecast] converting mp3's to aac+ or ogg
>> Hey Dave,
>> Personally I use ezstream as a source client as it's designed to 
>> re-encode your stream (it's available at www.icecast.org). I've set 
>> up my radio to re-encode my archived flacs to ogg vorbis then out to 
>> icecast and it works quite well.
>> As for quality, vorbis is apparently one of the nicer formats at low 
>> bitrates. I'm not sure about aac though, I'd imagine there isn't much 
>> in the way of support for it so you'd be much better off with ogg. 
>> Either way though, re-encoding from a lossy format (mp3) to another 
>> lossy format (ogg/aac) you'll notice some sound degradation from your 
>> source mp3, this is entirely why I archive in flac.
>> I'm not sure what you want to do for dialup/broadband quality 
>> settings but I'd probably just run two mounts for each station, one 
>> low bitrate and one higher. One thing you have to keep in mind though 
>> is that all this re-encoding would happen on the fly so you need to 
>> make sure the machine you'd be doing it with was up to the task.
>> Not sure if any of the above helps, but I'd imagine it presents some 
>> options at least.
>> Chris
>> Dave wrote:
>>> Hello,
>>>    I've got a FreeBSD 6 machine running icecast2 and ices0streaming 
>>> four different streams of mp3's. Now i have a need to stream the 
>>> same content as either aac+ or ogg vorbis whichever would be easiest 
>>> to set up and give the best quality. I want these new streams to 
>>> handle both broadband and dialup users without sacrificing quality. 
>>> My problem is i really really do not want to have to manually go 
>>> through my media again and bring them in to aac+ or ogg, doing it 
>>> once for mp3 was bad enough. I used abcde to handle this, and as i 
>>> said i'd like to find an automated way of reworking these files. Any 
>>> suggestions welcome.
>>> Thanks.
>>> Dave.
>>> _______________________________________________
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>>> Icecast at xiph.org
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